Effect of electrocautery vs. scalpel on fascial mechanical properties after midline laparotomy incision in rats.

BACKGROUND: The method of midline laparotomy incision and closure remains a complex surgical problem. OBJECTIVE: To compare the mechanical properties at the interface of midline laparotomy incision made by scalpel versus electrocuting current in rats. METHODS: A sharp midline laparotomy incision was made in 60 Wistar female rats using a scalpel or electrocautery to open the fascia. The fascial and skin wounds were closed separately with a continuous nylon. Fascial specimens were analyzed for mechanical properties at the midline incision using a loading machine. The load-extension curve was recorded during tensile loading at a steady extension rate of 15 mm/min. RESULTS: There was no statistically significant difference between the two groups in either wound-bursting force (PPEAK) or the strain energy spent until the point of measured PPEAK. Each load-extension curve showed a characteristic pattern in all rats. Tissue stiffness was greater in the scalpel group than in the electrocautery group (P = 0.02). Correlations were found between tissue stiffness and strain energy, between tissue stiffness and bursting force, and between bursting force and strain energy. CONCLUSIONS: While tissue stiffness was greater when a scalpel was used compared to electrocuting to incise the midline abdominal fascia in rats, there was no difference in the bursting force required to disrupt the wound.

The efficacy of oral deferiprone in acute iron poisoning.

Due to its high cost and need for parenteral administration, the standard iron chelator deferoxamine is not used in many individuals with acute and chronic iron poisoning worldwide. Deferiprone is the first oral iron chelator to be shown to be effective in chronically iron overloaded thalassemia patients. Its efficacy, by oral administration, in acute iron poisoning has not been tested. Our objective was to determine whether orally administered deferiprone can reduce the mortality of rats following acute, toxic, oral doses of iron. Rats were administered 612 mg/kg elemental iron orally, corresponding to LD50 in the species tested. Two other groups received the same oral dose of iron followed by oral deferiprone: 800 mg/kg and 800 mg/kg, followed by another dose of 800 mg/kg 2 hours later. Coadministration of 800 mg/kg deferiprone with the iron decreased mortality from 30% to 6.6% after 2 hours (P = .02), from 40% to 16.6% after 12 hours (P = .04), and from 53.3% to 20% after 24 hours (P = 0.007). Mortality was also significantly decreased among animals coadministrated 2 repeated doses of deferiprone of 800 mg/kg with iron, to 0%, 9%, and 18%, and 2, 12, and 24 hours postdrug administration, respectively (P = .04, .05, .04, respectively). Histologically, there was a dose-dependent decrease in iron accumulation in the gastrointestinal tract. Orally administered deferiprone can decrease morbidity and mortality caused by acute iron overdose in rats. Oral deferiprone holds promise in the treatment of iron poisoning in humans.

The effect of diazepam in the recovery of rabbits from acute acetaminophen intoxication.

We have recently shown that diazepam can reduce mortality of acute iron overdose in rats. The mechanism for that effect is not yet defined. Our objective in the present study was to assess whether diazepam can similarly reduce mortality of experimental acute acetaminophen intoxication. Survival of rabbits was compared among four groups receiving 3 g/kg (body weight) of acetaminophen (LD40) orally each, followed by: 1) nothing (group I), 2) one oral dose of 140 mg/kg N-acetylcystein (NAC) an hour later (group II), 3) intramuscular injection of 7 mg/kg diazepam (group III), 4) intramuscular injection of 7 mg/kg diazepam and one oral dose of 140 mg/kg NAC an hour later (group IV). 37.5% of rabbits in group I died after 16 hours, whereas none of the rabbits in group III died, (p = 0.04). No animal died during the 96-hour observation period in groups II and IV. Two and four hours post drug administration, acetaminophen plasma concentrations (APC) were significantly lower among rabbits in group III than in group I (p = 0.0007 and 0.01, respectively) and significantly lower among rabbits in group IV than in those in group II (p<0.0001 and p = 0.03, respectively). Acetaminophen plasma concentrations 2 hours after drug administration were also significantly lower among rabbits in group III than in those in group II (p = 0.0002). Seven and 24 hours after dosage, APC tended to be higher among rabbits in group III than in those in group I, but not significantly so. Administration of diazepam without NAC did not prevent liver and renal dysfunction. We conclude that early administration of diazepam in acute experimental acetaminophen overdose in rabbits reduced APC and mortality, probably by slowing intestinal motility, which resulted in delayed acetaminophen absorption from the gastrointestinal tract.

Absorption and elimination of alpha-thrombin and tranexamic acid after fibrin sealant application on resected livers in rabbits.

Maximum blood concentrations (Cmax) of thrombin and tranexamic acid were evaluated in the bloodstream after local application of a radioactively labelled cryoprecipitate based fibrin (CBF) sealant to a partial liver resection in rabbits. The Cmax of 3H-tranexamic acid reached a peak of 0.015 mg/ml of plasma after 1 h and then slowly cleared within 10 h, never reaching pharmacologically active systemic levels, and demonstrating a slow release from the clot and a fast clearance for the drug. The Cmax of 125I-alpha-thrombin never exceeded 56 milliunits of thrombin equivalent per ml, lower than endogenous thrombin generated in abdominal surgery. Furthermore, the low ratio of trichloroacetic acid precipitable counts versus total counts indicates that the majority of thrombin proteins are in a continuous process of degradation into very small peptides, which are known to be biologically inactive. The bioavailability of tranexamic acid, when embedded in a fibrin sealant, is much longer than when intravenously administered. Conversely, the circulating thrombin resulting from the sealant is low-molecular-weight degradation products with probably no significant biological activity.

Effect of very high single dose of cisplatinum and of radiation on the brain of the rabbit.

The importance of chemotherapy and radiotherapy for treating brain tumors, is well established. In a previous study, a rabbit's brain was treated with doses of up to 12 mg kg-1 of cisplatinum and 4000 cGy, without any morphological or pathological changes. The purpose of this study is to establish the effect of very high single doses of cisplatinum and radiation on the rabbit's brain, applied in 12, 16 and 18 mg kg-1, and 5000, 7500 and 8000 cGy, respectively. The general clinical and neurological condition of the rabbits was unaffected, but areas of alopecia and scalp ulcers appeared. Although these are very high doses of chemotherapy and radiotherapy, the histopathological and morphological examination of the rabbit's brain remained normal.

Acute iron intoxication: significant differences between sexes.

Iron, one of the common medications in use among children and adults, is the leading cause of pediatric unintentional ingestion fatalities and is not an uncommon poisoning among adults. Accidental ingestion is common because iron-containing compounds are readily available, brightly colored, often sugar coated, and frequently considered harmless vitamins. There are no data on differences between sexes with regard to iron intoxication, and the management of iron overdose is the same for females and males. After oral administration by gavage of the LD50 of iron to Wistar rats, the pharmacokinetics of iron, baseline and peak serum iron levels, and mortality rates were compared between sexes. Prepubertal females died significantly more than males (p < 0.01), pubertal females died significantly earlier than males (p < 0.04), and the same was true among adult rats (p = 0.02). Baseline serum iron levels were not significantly different between prepubertal female and male rats, but female pubertal rats had significantly higher baseline iron levels than males (p = 0.006). After iron administration, females had significantly higher peak serum iron concentrations (p < 0.03). Mechanisms of iron absorption are still not completely known and, probably, there are differences in iron absorption between sexes, which may account for the differences in serum iron levels and mortality rates. While the therapeutic approach in cases of intoxication is individual, iron intoxication, as may be true for other poisonings also, treatments administered to females may need to be different from that given to males.

Heliox therapy for pneumothorax: new indication for an old remedy.

STUDY OBJECTIVE: To evaluate a new method of treating pneumothorax: having the subject breathe a helium/oxygen mixture (heliox). METHODS: We conducted a prospective, randomized, controlled study of nine white rabbits weighing 2.5 to 3.5 kg. Experimental pneumothorax was induced in all rabbits with the injection of 20 mL of air into the pleural space. The rabbits then breathed heliox, oxygen, or room air for 2 hours. Chest radiography was performed 5 minutes after induction of pneumothorax, then at 1 and 2 hours. We determined pneumothorax size on the chest radiograph by measuring the interpleural distance and expressing it as a percentage of the hemithorax. RESULTS: At 2 hours the pneumothoraces in the heliox group had diminished from 17.50% +/- .50% to .17% +/- .29%; in the oxygen-breathing group they had diminished from 17.83% +/- 2.25% to .50% +/- .50%; and in the air-breathing group they had diminished from 18.50% +/- 3.12% to 17.33% +/- .25%. The difference between the air-breathing and the oxygen-breathing or heliox-breathing animals was highly significant; no significant difference was found between the oxygen and heliox groups (P<.0001). CONCLUSION: Heliox, a safe and convenient therapy, is as effective as oxygen in reducing the volume of an experimental pneumothorax in rabbits.

Effect of high simple dose of cisplatinum and of radiation on the brain of rabbit.

In former studies of intracarotid and intravenous administration of cisplatinum, separate and combined with brain irradiation, we found no cerebral damage. In this study, gradually increasing high doses (above the therapeutic ones) of cisplatinum were administered intravenously to one series of rabbits and increasing high amounts of irradiation (above the therapeutic amounts) were given to another series. Although the rabbits that received highest doses of irradiation developed areas of alopecia and skin ulcers on the head, the general clinical and histopathologic examination of the rabbits' brains in both series was normal. The purpose of this study was to establish the effects of high doses of intravenous cisplatinum and irradiation on the rabbits brains.

Effect of the combination of cisplatinum and radiation in the rabbit's brain.

The effect of cisplatinum as a potential radiosensitizer in brain tumors is controversial. We examined the effect of the combination of cisplatinum with radiation compared to radiation alone in rabbits' brain. All rabbits were irradiated and cisplatinum was injected intravenously into part of them. Therapeutic doses of cisplatinum and irradiation were given. The rabbits were euthanised at different intervals according to protocol. The general clinical and neurological condition of the rabbits was unaffected, and histopathological examination of the rabbit's brain was normal. The purpose of this study was to establish the effect of cisplatinum followed by cranial irradiation in therapeutic doses to the normal rabbit's brain.

Experimental septic arthritis in rabbits treated by a combination of antibiotic and steroid drugs.

OBJECTIVES: Intraarticular steroid injection is traditionally contraindicated during acute septic arthritis. However, there is abundant evidence which proves that the damage to the joint is not only due to the direct effect of bacteria, but also to the local protective mechanisms evoked by the organism. There is, therefore, theoretical justification for a combined therapy of systemic antibiotics and intraarticular corticostertoids in septic arthritis. METHODS: Experimental arthritis was induced by the intraarticular injection of Staphylococcus epidermidis in rabbits. The experimental scheme included three groups of animals: animals that were infected but not treated (group 1); animals treated with systemic antibiotics (group 2); and animals treated with systemic antibiotics and intraarticular steroids (group 3). Nine days later the animals were sacrificed and joint histopathological-histochemical indices were calculated. RESULTS: Animals from groups 2 and 3 had a smaller pannus, reduced proteoglycan loss, no loss of cartilage height and diminished synovial inflammation in comparison to the animals from group 1. The animals from groups 2 and 3 were identical in terms of cartilage cellularity, surface erosion, chondrocyte cloning, pannus formation and proteoglycan loss. Synovial inflammation appeared to be less pronounced in group 3 animals when compared to animals of group 2. CONCLUSION: Concomitant antibiotic-steroid treatment of septic arthritis seems to be harmless in this experimental setting.

Brain effect of intracarotid administration of cisplatinum.

The antitumoral effect of Cisplatinum is well known, including its effect on brain tumors. With the purpose of establishing the effect of intraarterial cis-dichlorodiammine platinum (CDDP) on the brain, Cisplatinum was injected in rabbits that were sacrificed at different intervals. The general clinical and neurological condition of the rabbits was unaffected, and histopathological examination of the rabbit's brain was normal.

Peritoneal ventilation in rabbits: augmentation of gas exchange with cisapride.

BACKGROUND: Peritoneal ventilation has been shown to be effective in achieving extrapulmonary oxygenation and carbon dioxide elimination in an animal model of severe adult respiratory distress syndrome (ARDS). Cisapride is a "prokinetic" agent (increases gastric emptying), that may increase the splanchnic circulation and thus favourably affect gas exchange in peritoneal ventilation. METHODS: Using Doppler ultrasound the effect of cisapride on the portal venous circulation was examined in eight spontaneously breathing rabbits and the effect of cisapride on gas exchange in five rabbits spontaneously breathing room air was compared with that of a control group who did not receive cisapride. Its effect on gas exchange in five rabbits with ARDS being treated with mechanical lung and peritoneal ventilation was compared with that of a control group, and its effect on gas exchange in five rabbits with ARDS treated with conventional ventilation was also compared with that of a control group. RESULTS: Enteral administration of cisapride increased portal venous blood velocity, as measured ultrasonographically, by a mean of 188% one hour after receiving the drug. In rabbits with ARDS being treated with both peritoneal ventilation and mechanical ventilation to the lungs, those receiving cisapride had arterial oxygen tensions 1.5-3 times that of controls. Cisapride had no effect on arterial blood gas tensions in rabbits who were spontaneously breathing room air, nor in rabbits with ARDS who received only conventional mechanical lung ventilation. CONCLUSIONS: Cisapride increases arterial oxygenation in rabbits with severe ARDS treated with peritoneal ventilation, probably due to its ability to increase splanchnic circulation. It should be considered as an adjuvant medication to peritoneal ventilation.

CT of renal densities caused by intravenous infusion of antibiotics.

OBJECTIVE: Patients treated with intravenous antibiotics were seen to have increased attenuation of the renal collecting system on CT scan of the abdomen. To detect whether this was related to certain antibiotics, we undertook a prospective study on patients being treated for sepsis while receiving intravenous antibiotics. In addition, we also tested antibiotics administered to rabbits. MATERIALS AND METHODS: Fourteen patients were tested with cefazolin, gentamicin, cefotaxime, vancomycin, amoxicillin and clavulanic acid (Augmentin), and metronidazole. Ten groups of rabbits received these drugs by intravenous injection. Computed tomography scan of the kidneys was performed prior to and 2 h after intravenous injection of antibiotics. Fourteen patients who underwent CT scan of the abdomen and were treated by intravenous antibiotics were scanned without contrast agent injection. RESULTS: According to our results, cefazolin, cefotaxime, and gentamicin seemed to be the most potent antibiotics in inducing increased attenuation of the collecting system. This effect was synergistic when a combination of drugs was used. CONCLUSION: The elucidation of the potential increase in attenuation of the collecting system by antibiotics in normally functioning kidneys should help to eliminate confusion with other pathologies such as medullary sponge kidney.

Peritoneal ventilation: an animal model of extrapulmonary ventilation in experimental adult respiratory distress syndrome.

Adult respiratory distress syndrome (ARDS) is a critical medical problem in which severe arterial hypoxemia is often poorly responsive to conventional modes of mechanical ventilation. We studied the efficiency of mechanical ventilation of the peritoneal cavity in rabbits with experimental ARDS caused by lung lavage. The study shows that peritoneal ventilation is significantly effective in oxygenation of hypoxemic animals with ARDS and is also effective for carbon dioxide elimination. Peritoneal ventilation may be considered as an investigational method for extrapulmonary oxygenation in severe intractable hypoxemia caused by ARDS.